About Markers

Markers are geometric features associated with a body and used to define the geometric position and orientation of motion elements, such as joints or springs.

This page discusses:

See Also
Creating Markers

Definition

A marker is a fixed reference system of coordinates created on a body. A reference system includes three axes perpendicular to each other: the x-, y-, and z-axes.

You can create two types of markers:

  • Manual marker: marker using an origin, position, and orientation specified by the user.
  • Geometry-based marker: marker using a geometric element as its origin to define its position and orientation.
Note: By default, a new body includes a body reference marker defined at the origin of the body. You cannot copy or delete this marker. You can create additional markers manually by defining specific positions and orientations.

To define a manual marker, specify its origin (axis system) and orientation, corresponding to a Euler, Extrinsic, or Cardan sequence.

For a geometry-based marker, you can select a geometric element as the origin of a marker. The position and orientation of the marker depends on the selected geometry.

Geometric Element Position Orientation
Axis-system Origin of the axis system —
Point (vertex) Point —
Line (linear edge) Midpoint Line direction
Circular edge Center Normal to the circle plane
Conical face Midpoint of the cone axis Axis direction
Cylindrical face Midpoint of the cylinder axis Axis direction
Planar face Centroid Normal to the plane
Spherical face Center —

You can also define the direction of the marker along the x, y, and z-axis by selecting one of the following types of geometries:

  • Line (linear edge)
  • Circular edge (arc)
  • Planar face
  • Cylindrical face
  • Conical face,
  • Axis from an axis system
  • Reference plane
  • Reference axis
Note: By default, the direction of the axes corresponds to the direction of the geometry selected as the origin.

You can also specify an offset for the position of the marker along each axis. This updates the position and orientation information of the marker automatically.

Tip: You can use the Robot to modify the position and orientation of the marker in the 3D area.

In the tree, markers appear under the corresponding Body nodes.

Automatic Markers

At the creation of a mechanism, the app defines joints using automatic markers. Automatic markers define the application point and orientation of a joint automatically, based on the definition of the associated engineering connection.

The joint position and orientation properties appear as computed and are not editable.

Note: To edit the position and orientation properties of a joint, use a manual marker.

The app computes the position of an automatic marker at the creation of the mechanism. You can modify the position of a product without changing its geometry, and update the product structure. In this case, the position of the automatic marker associated with the body reference marker remains the same.

You can use automatic markers to define the position and orientation of the following joints:

  • Rigid
  • Prismatic
  • Spherical
  • Revolute
  • Screw
  • Cylindrical
  • Planar
  • Universal
  • Point curve
  • Tangency curve

When using controlled joints, automatic markers are linked to the associated geometry and positioned on the controlled plane or line.